1/
meme chose avec write(1);

2/
#include<stdio.h>
#include<fcntl.h>
#include<unistd.h>
#include<stdlib.h>

#define szbuf 256

int main(int argc, char const *argv[])
{
	char buf[szbuf];
	int f1,f2,n,m;
	if(argc<3)
	{
		fprintf(stderr, "Usage : %s <SRC.FILE><TRUC.FILE>",argv[1]);
		exit(1);
	}
	f1 = open(argv[1],O_RDONLY);
	if(f1 == -1)
	{
		perror("Opening source file fails");
		exit(2);
	}
	f2 = open(argv[2],O_WRONLY|O_TRUNC|O_CREAT,0600);
	if(f2 == -1)
	{
		perror("Opening destination file fails");
		exit(3);
	}
	while(n = read(f1,buf,szbuf))
	{
		m = write(f2,buf,n);
		if(m == -1)
		{
			perror("Writing in file fails");
			exit(4);
		}
	}
	close(f1);
	close(f2);
	exit(0);
}

3/
#include<stdio.h>
#include<fcntl.h>
#include<unistd.h>
#include<stdlib.h>
#include <string.h>


#define szbuf 256

int main(int argc, char const *argv[])
{
	char buf[szbuf];
	int a, b, c, d;
	if(argc<2)
	{
		fprintf(stderr, "Usage: %s ./store_numb <file_name>",argv[1]);
		exit(1);
	}
	a = open(argv[1],O_WRONLY|O_TRUNC|O_CREAT,0600);
	if(a == -1)
	{
		perror("Opening destination file fails");
		exit(2);
	}
	b = open(argv[2],O_WRONLY|O_TRUNC|O_CREAT,0600);
	if(b == -1)
	{
		perror("Opening destination file fails");
		exit(3);
	}
	write(1,"Numb --> ",9);
	memset(buf,0,szbuf);
	while(b = read(0,buf,szbuf))
	{
		d = (int)strtol(buf,NULL,0);
		c = write(a,&d,sizeof(int));
		if(c == -1)
		{
			perror("Writing in file fails");
			exit(3);
		}
		memset(buf,0,szbuf);
		write(1,"Numb --> ",9);
	}
	close(a);
	exit(0);
}

4/
#include<stdio.h>
#include<fcntl.h>
#include<unistd.h>
#include<stdlib.h>
#include <string.h>


#define szbuf 256

int main(int argc, char const *argv[])
{
	char buf[szbuf];
	int a, b, c, d;
	if(argc<2)
	{
		fprintf(stderr, "Usage: %s ./store_numb <file_name>",argv[1]);
		exit(1);
	}
	a = open(argv[1],O_WRONLY|O_TRUNC|O_CREAT,0600);
	if(a == -1)
	{
		perror("Opening destination file fails");
		exit(2);
	}
	write(1,"Numb --> ",9);
	memset(buf,0,szbuf);
	while(b = read(0,buf,szbuf))
	{
		d = (int)strtol(buf,NULL,0);
		c = write(a,&d,sizeof(int));
		if(c == -1)
		{
			perror("Writing in file fails");
			exit(3);
		}
		memset(buf,0,szbuf);
		write(1,"Numb --> ",9);
	}
	close(a);
	exit(0);
}